To a mixture of ethyl 5-fluoro-4-oxo-1,4-dihydroquinoline-3-carboxylate (0.050 g, 0.21 mmol), potassium carbonate (0.088 g, 0.64 mmol) and potassium iodide (3 mg, 0.02 mmol) was added the above 2-(bromomethyl)-6-fluoronaphthalene in 1 mL of DMF. The reaction was stirred overnight at 40° C. and 1 mL of a saturated aqueous lithium hydroxide solution was then added to the reaction. After stirring for 30 min, the solution was acidified with 4 N HCl and the product was extracted three times with EtOAc. The combined organic layers were dried over sodium sulfate, filtered and concentrated in vacuo. The crude material was purified by reverse phase HPLC to provide the 5-fluoro-1-[(6-fluoro-2-naphthyl)methyl]-4-oxo-1,4-dihydroquinoline-3-carboxylic acid which gave a mass ion (ES+) of 366 for M+H+.
